fix: use new path for streamingnode recovery info (#38516)

issue: #38399

Signed-off-by: chyezh <chyezh@outlook.com>

internal/metastore/catalog.go

@@ -214,7 +214,12 @@ type StreamingCoordCataLog interface {
 
 // StreamingNodeCataLog is the interface for streamingnode catalog
 type StreamingNodeCataLog interface {
+	// WAL select the wal related recovery infos.
+	// Which must give the pchannel name.
+
+	// ListSegmentAssignment list all segment assignments for the wal.
 	ListSegmentAssignment(ctx context.Context, pChannelName string) ([]*streamingpb.SegmentAssignmentMeta, error)
 
+	// SaveSegmentAssignments save the segment assignments for the wal.
 	SaveSegmentAssignments(ctx context.Context, pChannelName string, infos []*streamingpb.SegmentAssignmentMeta) error
 }

internal/metastore/kv/streamingnode/constant.go

@@ -1,7 +1,8 @@
 package streamingnode
 
 const (
-	MetaPrefix             = "streamingnode-meta"
+	MetaPrefix = "streamingnode-meta"
-	SegmentAssignMeta      = MetaPrefix + "/segment-assign"
+
-	SegmentAssignSubFolder = "s"
+	DirectoryWAL           = "wal"
+	DirectorySegmentAssign = "segment-assign"
 )

internal/metastore/kv/streamingnode/kv_catalog.go

@@ -15,7 +15,22 @@ import (
 	"github.com/milvus-io/milvus/pkg/util/etcd"
 )
 
-// NewCataLog creates a new catalog instance
+// NewCataLog creates a new streaming-node catalog instance.
+// It's used to persist the recovery info for a streaming node and wal.
+// The catalog is shown as following:
+// streamingnode-meta
+// └── wal
+//
+//	├── pchannel-1
+//	│   └── segment-assign
+//	│       ├── 456398247934
+//	│       ├── 456398247936
+//	│       └── 456398247939
+//	└── pchannel-2
+//	    └── segment-assign
+//	        ├── 456398247934
+//	        ├── 456398247935
+//	        └── 456398247938
 func NewCataLog(metaKV kv.MetaKv) metastore.StreamingNodeCataLog {
 	return &catalog{
 		metaKV: metaKV,
@@ -27,6 +42,7 @@ type catalog struct {
 	metaKV kv.MetaKv
 }
 
+// ListSegmentAssignment lists the segment assignment info of the pchannel.
 func (c *catalog) ListSegmentAssignment(ctx context.Context, pChannelName string) ([]*streamingpb.SegmentAssignmentMeta, error) {
 	prefix := buildSegmentAssignmentMetaPath(pChannelName)
 	keys, values, err := c.metaKV.LoadWithPrefix(ctx, prefix)
@@ -81,15 +97,16 @@ func (c *catalog) SaveSegmentAssignments(ctx context.Context, pChannelName strin
 }
 
 // buildSegmentAssignmentMetaPath builds the path for segment assignment
-// streamingnode-meta/segment-assign/${pChannelName}
 func buildSegmentAssignmentMetaPath(pChannelName string) string {
-	// !!! bad implementation here, but we can't make compatibility for underlying meta kv.
+	return path.Join(buildWALDirectory(pChannelName), DirectorySegmentAssign) + "/"
-	// underlying meta kv will remove the last '/' of the path, cause the pchannel lost.
-	// So we add a special sub path to avoid this.
-	return path.Join(SegmentAssignMeta, pChannelName, SegmentAssignSubFolder) + "/"
 }
 
 // buildSegmentAssignmentMetaPathOfSegment builds the path for segment assignment
 func buildSegmentAssignmentMetaPathOfSegment(pChannelName string, segmentID int64) string {
-	return path.Join(SegmentAssignMeta, pChannelName, SegmentAssignSubFolder, strconv.FormatInt(segmentID, 10))
+	return path.Join(buildWALDirectory(pChannelName), DirectorySegmentAssign, strconv.FormatInt(segmentID, 10))
+}
+
+// buildWALDirectory builds the path for wal directory
+func buildWALDirectory(pchannelName string) string {
+	return path.Join(MetaPrefix, DirectoryWAL, pchannelName) + "/"
 }

internal/metastore/kv/streamingnode/kv_catalog_test.go

@@ -41,3 +41,14 @@ func TestCatalog(t *testing.T) {
 	})
 	assert.NoError(t, err)
 }
+
+func TestBuildDirectory(t *testing.T) {
+	assert.Equal(t, "streamingnode-meta/wal/p1/", buildWALDirectory("p1"))
+	assert.Equal(t, "streamingnode-meta/wal/p2/", buildWALDirectory("p2"))
+
+	assert.Equal(t, "streamingnode-meta/wal/p1/segment-assign/", buildSegmentAssignmentMetaPath("p1"))
+	assert.Equal(t, "streamingnode-meta/wal/p2/segment-assign/", buildSegmentAssignmentMetaPath("p2"))
+
+	assert.Equal(t, "streamingnode-meta/wal/p1/segment-assign/1", buildSegmentAssignmentMetaPathOfSegment("p1", 1))
+	assert.Equal(t, "streamingnode-meta/wal/p2/segment-assign/2", buildSegmentAssignmentMetaPathOfSegment("p2", 2))
+}